Under the Rochester Epidemiologic Program Project (REPP), a unique population-based data source, covering the medical histories of the Olmsted County population throughout their local residence has been developed. This central diagnostic index has served as the basis for over 180 epidemiologic studies on a myriad of topics--many relating to critical health issues of national importance, and all with excellent case ascertainment. The research facility has been used not only by the REPP staff, but by many clinical and public health colleagues both within and outside of the Mayo Clinic. The REPP provides population-based data for several other major program projects, including the Comprehensive (Minn.) Epilepsy Center and the Mayo Stroke Center. The continued updating of the central diagnostic index is essential to preserve this research potential. In the near future it will be necessary to obtain support for our epidemiologic program from the several categorical institutes of NIH. The purpose of this continuation proposal is to apply for funds which will allow for an orderly transition without a breakdown of the basic system. In this proposal, we request funding for: 1) Continued supplementation of the Mayo Clinic diagnostic index with data from the Olmsted Medical group, Olmsted Community Hospital and several other non-Mayo sources of medical care in Olmsted County; 2) The development, from the medical records, of an Olmsted County population frame to permit unbiased selection of controls for case-control studies; 3) Development of methodology within the data base for studies of familial aggregation; 4) Continued support for epidemiologic projects now nearing completion, such as rheumatic fever, prostate cancer, cholelithiasis, etc.; and 5) New studies in limb fractures and trauma to the nervous system.